Proximal and distal causes of land degradation:
The causes of desertification, in general, may be divided into proximal and distal reasons. These are explained below.
The proximal are biophysical in terms of the vulnerability of soils due to topography and climatic factors such as temperature, rainfall and wind, but also due to unsustainable land management practices.
Unsustainable forest management results from deforestation, degradation, overgrazing, and conversion to other land uses, forest fires, excessive fuel wood collection and unsustainable harvests of non-timber forest. In the Indian context, forest degradation rather than deforestation is one of the major reasons for land degradation.
Unsustainable agricultural practices result from extensive and frequent cropping, excessive fertilizer and pesticide use and shifting cultivation with short fallows. Decreases in soil fertility often result from prolonged cultivation and erosion, and extensive application of fertilizers is used to maintain crop yields.
Expansion of canal irrigation to arid and semi-arid areas has caused widespread salinization and water logging. Mining and quarrying also inevitably result in land degradation particularly if inadequate land restoration measures are taken.
The distal reasons which precipitate or exacerbate land degradation are far more systemic. These include weak institutions and poor governance, policy and market failures (e.g. subsidizing fertilizer use), land fragmentation and uncertain tenure, demographic and socio-economic factors as well as the impacts of globalization.
Escalating demands for products in areas far removed from where they are produced is often responsible for inappropriate policies and land use practices. This makes the externalization of environmental and social costs a huge risk in this age of globalisation.
Poor governance that fails to recognize or promote traditional, community-based land management systems, decentralisation and institutions based on traditional knowledge can aggravate land degradation.
Soil Quality and Soil Carbon:
Soil quality is important for two reasons. First, unscientific use of soil can damage itself and the ecosystem; therefore, we need to match the management of land to the soil’s capability. Second, we need to establish a baseline understanding about soil quality so that we can recognize changes as they occur.
Soils are a major carbon reservoir comprising more carbon than the atmosphere and terrestrial vegetation combined. Soil Carbon is the backbone of soil fertility. Soil carbon includes both inorganic carbon as carbonate minerals, and as soil organic matter. Many tropical soils are poor in inorganic nutrients and rely on the recycling of nutrients from soil organic matter.
Soil organic carbon (SOC) is the engine of any soil and plays an important role in maintaining fertility by holding nitrogen, phosphorous and a range of other nutrients. It helps in improving soil properties such as water-holding capacity and providing gaseous exchange and root growth. The loss of SOC indicates a certain degree of soil degradation and soil degradation is a severe problem in countries like India with high demographic pressure.
However, if more amount of carbon is stored in the soil as organic carbon, it will reduce the amount present in the atmosphere, and therefore help to alleviate the problem of global warming and climate change. The process of storing carbon in soil is called “soil carbon sequestration”.
Restoring the quality of degraded soils is a challenging task, especially in regions dominated by small, resource-poor landholders. Re-carbonization of the depleted SOC pool, which is essential to numerous functions, requires regular input of biomass-C and essential elements (i.e., N, P, and S).
Evolution of land resource management policies and approaches:
Though the subjects of “land”, “agriculture” and “water” are subjects with the States as per the Constitution, the concerns for arresting and reversing land degradation and desertification have been reflected in many of the national policies for nearly 40 years.
Current policies and key legislation include The National Water Policy 2012; National Forest Policy 1988; National Agricultural Policy 2000; Forest (Conservation) Act 1980; Environment (Protection) Act 1986; National Environmental Policy 2006; National Policy for Farmers 2007; National Agroforestry Policy 2014 etc which have enabling provisions for addressing these problems.
The evolution of schemes and programmes to address the various aspects of land degradation actually reflect the progressive acquisition of knowledge and development of improved packages of practice, as well as the shifts in focus based on national priorities. Some of the key milestones along this process include:
- Adoption of watershed approach and planning based on micro-watersheds; use of remote sensing data and spatial data in planning at the micro-watershed level
- Integrated treatment incorporating contouring, gully plugging, vegetative as well as engineering-based solutions for soil-moisture conservation, covering agricultural as well as non-agricultural lands. Joint Forest Management (JFM) and Social Fencing by involving local communities.
- Integrated farming-based approach incorporating fodder and fuelwood supply, farm-forestry and agroforestry and silvi-pastures; stall feeding, improved chullahs etc.
- Focus on water management, aquifer recharge and water budgeting as well as crop planning
- Focus on social aspects: participative planning at micro-watershed level; transect walk; Constitution of Watershed Committee under the Gram Sabha; Water User Association development; social audit.
- Incorporation of livelihood related activities and development of micro-enterprises; involvement of Self-Help Groups (SHGs); programmes such as Mahila Kisan Sashaktikaran Pariyojana (MKSP) focusing on increasing capabilities women farmers with a view to increasing sustainability.
- Adoption of climate-adaptation related solutions both with regard to floods and intense precipitation as well as temperature and moisture stress, and orienting employment generation programmes like MGNREGA in this direction.
- Increasing the role of Panchayati Raj Institutions (PRIs) and ensuring “convergence” between Government programmes and programmes executed by PRIs.
There are three basic strategies of restoring soil quality
- minimizing losses from the pedosphere or soil solum – minimising top soil loss
- creating a positive soil C budget, while enhancing biodiversity; and
- strengthening water and elemental cycling. (Element cycles are the biogeochemical pathways by which elements are transformed and moved through various states by geological and biological processes. E.g., Carbon Cycle, Nitrogen Cycle).
Soil Erosion: A major factor responsible for the degradation of the natural resources is soil erosion. In general, soil erosion is more severe in mountainous than in undulating and plain areas. Inappropriate soil management, unsuited to the location like tilling along the slope, lack of crop cover during heavy rainfall, etc. is responsible for accelerated soil erosion with consequent loss of land productivity.
Because of different processes like slaking and dispersion, mechanisms of soil structural collapse and degradation vary climatically and from one soil type to another. Soil erosion by water is one of the most serious degradation in the Indian context.
Improving Soil/Agro-Biodiversity: Soil biota are important to soil quality and reduce risks of degradation and desertification. Indeed, soil biota comprise a major component of global terrestrial biodiversity and perform critical roles in key ecosystem functions (e.g., biomass decomposition, nutrient cycling, moderating CO2 in the atmosphere, creating disease suppressive soils, etc.). Improving activity and species diversity of soil fauna and flora (micro, meso and macro) is therefore essential to restoring and improving soil quality and reducing risks of soil degradation.
The importance of macro-organisms (e.g., earthworms, termites) for restoring soil quality has been widely recognized for centuries. Risks of soil degradation can be mitigated through adoption of land use and management systems which improve soil biological processes, and introduction of beneficial organisms into soils by selective inoculation.
For these and other reasons, the presence of earthworms, termites and other soil biota are often identified as important indicators of quality in tropical soils.
Soil Restorative Farming/Cropping Systems: Similar to arable lands, managing quality of rangeland soils is also essential for reducing risks of degradation. Sustainable management of rangeland soils is especially challenging because of high variability, harsh environments, and the temptation for over-grazing.
Improving Soil Resilience: The term soil resilience refers to the ability of the soil to recover its quality in response to any natural or anthropogenic perturbations. Soil resilience is not the same as soil resistance, because resilience refers to “elastic” attributes that enable a soil to regain its quality upon alleviation of any perturbation or destabilizing influence. There are also some organic management options for reducing soil degradation risk and improving human health, that may have site-specific niches.
Salinization and Alkalization: The expansion of irrigation has been one of the key strategies in achieving self-sufficiency in food production. In most of the expansion, the area is increased under canal irrigation that leads to rise in groundwater Table resulting in the soil deterioration through accumulation of salts.
Acidity: The largest areas covered by acid soils in India belong to laterites and various latosol soils. The management of acid soils include
(a) addition of lime and/or other chemical amendments to correct the acidity and manipulate the agricultural practices so as to obtain optimum crop yields,
(b) grow acid tolerant crops and cultivars/varieties and to supplement nutrients through suitable carriers, and
(c) water management and other agronomic practices.
Light and frequent irrigation practice helps in enhancing water and nutrient-use efficiency on these soils. Problems of high evaporative demands on crusting soils can be managed by mulching the crop lands with available paddy straw. Mulching not only lowers evapo-transpiration of the crops but also saves irrigation water to the tune of 15-20 % in different crops.
Loss of soil Carbon: Removal or in-situ burning of crop residues, no or least addition of organic manures, and intensive cultivation are the major reasons for the depletion of soil organic carbon. Balanced and integrated use of inorganic and organics, management of crop residues, etc. are desirable options for sequestering organic carbon in soil.
Nutrient Imbalance: Nutrient losses could occur in many ways, i.e., via emission to the air as NH3, N2O, NO, and N2, and discharge to the water through runoff, leaching and erosion. The wide use of fertilizer and booming developed of the livestock production contributed to the vast N losses to the environment.
Both of the N imbalance and the N losses can be improved greatly, without sacrificing the crop yield, such as balanced and integrated use of fertilizers and organic manures, which are effective in increasing crop yields, nutrient use efficiency and minimizing environmental impacts.
Pollution/Contamination by Toxic Substances: Both geogenic and anthropogenic factors cause pollution/contamination of soil and water resources. However, their impact varies with rainfall pattern, and depth and geology of aquifer.
Unfinished tasks and the way forward:
Though it would seem that there has been very substantial development with regard to the national imperative of checking land degradation, the visible impact of programmes on the ground is clearly less than impressive. A provisional diagnostic would suggest:
- Lack of consistency in data collection as impact assessments are carried out by different agencies from those implementing the project and hence project implementers view these evaluations as an external issue.
- Failure to evaluate non-market and societal co-benefits that provide a more holistic picture of these programmes
- Lack of post-project monitoring and impact assessments to evaluate the contribution of these projects to building resilience to drought and long-term restoration of ecosystems.
- Insufficient coverage by government programmes for addressing land degradation primarily because of funding constraints but also because of management and technical capacity constraints.
- Need to focus on more sustainable agricultural practices. Depleting groundwater, the spread of problem soils (acidic, saline & alkaline), loss of soil organic carbon (SOC) and yield plateaus manifest the different dimensions of the problem and challenge.
- Perverse incentives such as free power for groundwater pumping; nitrogenous fertilizer subsidy; Minimum Support Price (MSP) only for a few crops (thus influencing crop choice) etc. may be causing degradation of additional areas.
In the last analysis sustainable management of land (and water) resources have to be by, and in close collaboration with, local communities. It is no coincidence that the few outstanding examples of sustainable management are all traceable to visionary local leadership supported by the host communities and assisted by public policies for sustainable use of resources, infrastructure creation, knowledge accretion and transmission, and development of entrepreneurship.
Checking and reversing land degradation has to be essentially based on self-regulatory practices with regard to a sustainable use of resources and energy. The task of public policies must include incentivisation of such regulation.